凉粉草种质资源的基因型鉴定、遗传多样性评价及优异种质筛选研究

Mesona chinensis, an important edible and medicinal plant, is used as raw materials for food industry in China. Although it has an urgent need to breed new varieties in cultivation, the knowledge of genetics and effective utilization method on germplasm resources is insufficient for this plant. This project will systematically collect germplasm resources including wild and cultivated populations of M. chinensis in China. Phenotypic variation of important agronomic traits related to yield and quality will be studied based on field experiments. Using RAD-seq, a set of SNP markers will be discovered and be used to identify the germplasm collections and their genetic diversity based on GBS technique at genomic level. The aims of the project are (1) genotyping for characterization of genotypes and identifying their phenotypic variations; (2) evaluating genetic diversity and their genetic relation, exploring the impact of their origin of cultivation, geographical distribution and reproductive mode on domestication history; (3) evaluating their breeding value of the collected germplasm resources systematically, and screening some excellent germplasm materials from them. Up to now, this study will be the most systematical research work involved germplasm resources collection, characterization, evaluation and screening of M. chinensis. The results of the project not only have significance for breeding M. chinensis new varieties with good quality-related traits for different industry application, but also provide experience for other medicinal plants to improve their cultivated varieties.

凉粉草（Mesona chinensis）是我国重要的药食两用植物和食品工业原料。种植中亟需培育凉粉草新品种，但目前对其种质资源的遗传背景和有效利用途径尚缺乏深入认识。本课题拟系统收集我国凉粉草野生和栽培种质资源，通过田间试验研究其重要农艺性状的表型变异；利用RAD-seq技术开发SNP分子标记，并基于GBS技术在基因组水平对其开展种质鉴定和遗传多样性研究。目的是：（1）鉴定种质材料的基因型及其表型变异；（2）评价种质材料的遗传多样性及其遗传关系，探讨栽培起源、地理分布和繁殖方式等因素对凉粉草驯化历史的影响；（3）全面评价凉粉草种质资源的育种价值，发掘优异的种质材料。本研究将是目前对我国凉粉草种质资源最为系统的收集、鉴定、评价与筛选工作，其结果不仅对选育满足不同工业原料需求的凉粉草新品种有重要意义，而且对我国其他药用植物品种改良研究也将起到重要的示范作用。

凉粉草（Mesona chinensis）是重要的药食两用植物。目前，对其遗传背景尚缺乏深入认识。本课题从华南地区收集了36个凉粉草居群，并对其开展了表型变异、遗传变异和优异种质筛选等研究。表型变异研究结果表明，各居群在形态和化学成分上存在着显著的差异(p < 0.01)；各形态性状在居群间普遍变异，其变异幅度为15.76% - 54.18%；干草产量主要与一些茎的性状正相关；总酚含量和总黄酮含量的变异范围分别为5.49 - 18.44 和 5.06 - 11.47 mg.g−1；抗氧化性（ABTS和DPPH）的变异范围为63.91 - 223.41 和 30.35 - 137.84 mmol Trolox equivalents.g−1；大多数居群含有丰富的多糖。在产量和质量方面表现最优的居群为GD-1, GD-2, GD-8, FJ-6, FJ-3, FJ-2, JX-6, GD- 7, JX-3, and JX-2。基于SLAF-seq技术，获得了16,651个可靠的多态SNPs。遗传变异研究结果显示，在物种水平(He=0.207)和居群水平(He=0.023–0.162) 凉粉草的遗传多样性均较低，表明该作物的遗传基础狭窄。FST和AMOVA分析结果则显示居群间有较大的遗传分化(FST = 0.483; 79.18% AMOVA)。STRUCTURE和聚类分析结果表明36个居群可分为4个遗传群组，预示着我国的凉粉草种质可能来源于不同的祖先谱系。优异种质筛选研究结果显示基于主成分分析法和灰度关联分析法的综合评定，从所有居群中筛选出10株凉粉草优良单株（SZ-1, SZ-2, SZ-3, WP2-1, WP2-2, WP2-3, XN-1, XN-2, XN-3和XY-1）。这些优良单株在产量和质量方面具有显著的优异性，可作为良种选育或快速扩繁的基础材料。本项目的研究结果对于凉粉草的种质资源保护和未来的育种工作具有重要意义。